A satellite image showed a recent Infinite Sun Energy client’s sloped roof with the peak running exactly north and south. This seemed to leave nothing but a due west or due east roof orientation in direct sunlight for an ISE solar energy system. The southern edge of the home, at least from the satellite, seemed hidden by shade, trees and other vegetation (see below). “Not a good candidate for solar” I thought.
Nevertheless, the owner wanted a site evaluation.
Upon visiting the site, I could see what had been hidden from the satellite; a hip roof with a sizeable triangular portion facing due south. In person, it was clear this roof was actually only partially shaded and large enough for a significant solar installation.
Two more factors worked in the homeowner’s favor for solar. First, he owns the trees and bushes shading the south-facing roof, so he is in control of the shade on his house, and second, he pays one of PG&E’s premium rate plans. Any photovoltaic solar solution he installs would shave off at least part of the most expensive energy he buys. Turns out this owner knew what he was doing when he called us.
A shade evaluation, using a Solmetric SunEye solar shade analyzer, revealed that even with the current trees, his south-facing roof had 71% insolation. Said another way, the “invisible” roof was really only 29% shaded each day on average. That’s plenty of available sunlight under the circumstances. Amazingly, the small solar system we designed for this owner still pays for itself in a reasonable time frame, offsets 25% of his high electric bill and enhances the value of his home more than the price he’ll pay for the system after his federal tax credit and state rebate.
Now, let’s see about carefully trimming some trees…
(Photo Google Earth)
